1. Field of the Invention
The invention relates to a process for shaping a body with elongate structures, such as in particular depressions, on its surface, and to bodies produced using the process and to devices comprising bodies of this type. Moreover, the invention relates to an apparatus for carrying out the process for shaping a body of this type.
2. Description of Related Art
It is known for optical fibers to be drawn from fiber preforms in the heated state and thereby to obtain greatly reduced fiber cross sections for optical waveguides.
In the field of microsystems technology, processes aim to introduce very fine structures into various materials. The structures are usually punctiform or linear elevations or depressions. In the finished components, these structures are used, for example, as passages for controlling very fine flows of liquid or gas.
In many applications, these structures are formed uniformly over the entire component in one direction, for example in the longitudinal direction, for example in the form of continuous passages or ribs. Components of this type are included, for example, in miniaturized heat exchangers or in components which are used to move optical fibers into a defined position and then hold them in place in this position.
Furthermore, PCT/JP 00/07955 describes a process for producing lenses which are substantially in rod form, in which reduced cross sections of a blank are obtained by redrawing this blank. Both the abovementioned fibers and the substantially rod-like lenses are each rounded on the outside, which is extremely favorable for the shaping of heated glass, since rounding of this nature can be formed automatically by viscous materials on account of their surface tension, and are therefore assisted during shaping.
DE 39 02 988 A1 describes a process for producing a support, which is provided with a groove, for an optical waveguide connector, in which the V groove is ground in with an aperture angle of approximately 90°, and the preform, after suitable heating, is drawn to a diameter of approximately 1/10 of the original diameter. If appropriate, further recesses are provided. However, the process appears in need of improvement with regard to the yield and with regard to the tolerances which can be achieved.
FR 2 788 267 A1 relates to a process for producing glass spacers, in which a mother glass with a cross section which is similar to the desired cross section, in a heated state at a viscosity of from 105 to 109, is drawn, and in which the drawn glass is cut into a large number of glass spacers.
EP 0 929 101 A1 describes a stamp for the press-forming of glass elements with a platinum film.
DE 197 36 732 A1 describes a device and process for machining a workpiece by means of laser light.
Furthermore, FR 2 505 472 describes an apparatus for producing optical fibers with a device for concentrating infrared energy.
Silicon substrates with V grooves which have been produced by etching are in widespread use in optical information and communications technology in order in this way to achieve precisely predefined lateral spacings. In this context, it is extremely advantageous that the lateral positioning accuracy is substantially defined by crystallographic planes in the silicon and that it is possible to use highly accurate photolithographic processes. However, a drawback is the fixed angle of the V-shaped groove, which is substantially predetermined by the crystallographic orientation of the silicon and selective etching rates during photolithographic patterning. The high price of both the silicon substrates, which are substantially in single crystal form, and of the photolithographic processes represent significant obstacles to inexpensive mass production.
By contrast, when a structured preform is being drawn out or redrawn, the problem arises that the initial drawing does not lead to the structures of the preform being deformed to scale, and consequently for many applications the shape of the preform cannot be reproduced with sufficient accuracy in the drawn workpieces. For example, it is known from GB 2 108 483 A that shape changes of this type are dependent, inter alia, on the temperature, the cross section of the preform, the tensile force used for drawing and the viscoelastic properties of the preform material. Deformations which may occur during redrawing include pin-cushion deformations, which lead to a concave curvature of surfaces which were originally planar, and also to edge rounding. The influence of the drawing temperature on the type of deformation, concave or convex, is also known, inter alia, from U.S. Pat. No. 5,721,050.
In GB 2 108 483 A, it is to this end proposed that the changes in shape be taken into account during production of the preform. However, since the effects of the change in shape are dependent on the size of the drawn parts and/or the size ratio of preform to drawn components, neutralization of the deformation effects is only achieved accurately at a specific scale ratio. To obtain reproducible results, therefore, it is also necessary for other parameters, such as tensile force and temperature, to be complied with.